A safer society can be realized when a detection target such as a suspicious person or a criminal can be reliably detected in a crowd. Thanks to progress in a face authentication technology and the like, authentication of a detection target from an image captured by a surveillance camera or the like has become feasible in recent years. By using the face authentication technology, a detection target can be extracted from an image captured by a surveillance camera.
Further, development of an interface device combining a projector with a camera has been under way in recent years. Such an interface device provides an interactive operation by detecting, with a camera, a manipulation performed on an image projected from a projector. NPL 1 discloses an interface device combining a projector with a camera.
For example, when the interface device is configured as a wearable device, and a user attached with the device moves around on the streets, a detection target can be detected from image data captured by the camera, and light for marking can be projected on the detection target from the projector.
In general, authentication processing such as object authentication and face authentication is heavy. Accordingly, when an interface device configured as a wearable device recognizes a detection target and takes some action on the detection target, a processing speed of an arithmetic device that can be equipped on the wearable device may be insufficient. Further, a scheme that the interface device transmits acquired image data to a server, and the server performs high-speed processing and returns positional information of the detection target to the interface device may be considered. However, real time action may not be taken on the detection target due to a communication delay. When real time action cannot be taken, the detection target may go out of an angle of view of a camera due to the target object moving or a person attached with the wearable device changing direction, thus causing a state that the detection target cannot be recognized.
PTL 1 discloses a tracking point detection device that reliably tracks a tracking point by lightening an image including the tracking point and further thinning out frames. The device in PTL 1 detects the tracking point included in thinned-out frames from both a forward direction and a reverse direction temporally, and determines coordinates of the tracking point in the image before frames are thinned out.
PTL 2 discloses an imaging device that generates display information providing a warning not to cause a tracking target to go out of frame, and displays the display information associated with the tracking target on a display screen.
PTL 3 discloses a surveillance system that performs face authentication by using a facial image of a visitor to a game arcade and associates positional information of the visitor with the facial image. The system in PTL 3 checks the facial image of the visitor against a facial image of an improper player, and when the visitor is an improper player, makes a report.